Cancer is the leading cause of death in developed countries and the second leading cause of death in developing countries. Deaths from cancer worldwide are projected to continue rising, with an estimated 12 million deaths in 2030. While substantial progress has been made in developing effective therapies, there is a need for additional therapeutic modalities that target cancer and related diseases.
The complexity of cancer disease arises after a selection process for cells with acquired functional capabilities to enhance survival and/or resistance towards apoptosis and a limitless proliferative potential. In addition, bi-direction interaction of cancer cells and stromal cells provides further advantage of cancer cell survival and distant metastasis to the secondary organs and tissues [Liotta L A, Kohn E C. The microenvironment of the tumour-host interface. Nature 411:375, 2001]. Furthermore, cancer stem cells (CSCs) represent the apex in the hierarchical model of tumor genesis, heterogeneity and metastasis. CSCs possess the capacity for unlimited selfrenewal, the ability to give rise to progeny cells, and also an innate resistance to cytotoxic therapeutics [Corbin E. Meacham and Sean J. Morrison. Tumour heterogeneity and cancer cell plasticity. [Nature 501:328, 2013]. Thus, there is need to develop drugs for cancer therapy addressing distinct features of established tumors.
The discovery that Drosophila segment polarity gene Wingless had a common origin with the murine oncogene Int-1 led to intensive studies on Wnt signalling pathway and identification of 19 mammalian Wnts and 10 Wnt receptors [Rijsewijk F, Schuermann M, Wagenaar E, Parren P, Weigel D, Nusse R. The Drosophila homolog of the mouse mammary oncogene int-1 is identical to the segment polarity gene wingless. Cell. 1987; 50: 649-57.]. Wnts are secreted glycoproteins which bind to cell surface receptors to initiate signaling cascades. Wnt signaling cascades have classified into two categories: canonical and non-canonical, differentiated by their dependence on β-catenin. Non-canonical Wnt pathways, such as the planar cell polarity (PCP) and Ca2+ pathway, function through β-catenin independent mechanisms. Canonical Wnt signalling is initiated when a Wnt ligand engages co-receptors of the Frizzled (Fzd) and low-density lipoprotein receptor related protein (LRP) families, ultimately leading to β-catenin stabilization, nuclear translocation and activation of target genes [Angers S, Moon R T. Proximal events in Wnt signal transduction. Nat Rev Mol Cell Biol. 2009; 10: 468-77. 68. Cadigan K M, Liu Y I. Wnt signaling: complexity at the surface. J Cell Sci. 2006; 119: 395-402. 69. Gordon M D, Nusse R. Wnt signaling: multiple pathways, multiple receptors, and multiple transcription factors. J Biol Chem. 2006; 281: 22429-33. 70. Huang H, He X. Wnt/beta-catenin signaling: new (and old) players and new insights. Curr Opin Cell Biol. 2008; 20: 119-25. 71. Polakis P. The many ways of Wnt in cancer. Curr Opin Genet Dev. 2007; 17: 45-51. 72. Rao T P, Kuhl M. An updated overview on Wnt signaling pathways: a prelude for more. Circ Res. 2010; 106: 1798-806].
In the absence of Wnt stimulus, β-catenin is held in an inactive state by a multimeric “destruction” complex comprised of adenomatous polyposis coli (APC), Axin, glycogen synthase kinase 3β (GSK3β) and casein kinase 1α (CK1α). APC and Axin function as a scaffold, permitting GSK3β- and CK1α-mediated phosphorylation of critical residues within β-catenin. These phosphorylation events mark β-catenin for ubiquitination recognition by the E3 ubiquitin ligase β-transducin-repeat-containing protein and lead to subsequent proteasomal degradation [He X, Semenov M, Tamai K, Zeng X. LDL receptor-related proteins 5 and 6 in Wnt/beta-catenin signaling: arrows point the way. Development. 131:1663, 2004. Kimelman D, Xu W. beta-catenin destruction complex: insights and questions from a structural perspective. Oncogene 25: 7482, 2006.].
In the presence of Wnt stimulus, Axin, GSK3β and Dvl are recruited to the co-receptor complex Fzd and LRP5/6 and lead to disruption of the β-catenin destruction complex. Therefore, β-catenin is stabilized and translocated to nucleus. Once in the nucleus, β-catenin forms a complex with members of the T-cell factor/lymphoid enhancer factor (TCF/LEF) family of transcription factors, recruiting co-factors such as CBP, p300, TNIK, Bcl9 and Pygopus, and ultimately driving transcription of target genes including c-myc, Oct4, cyclin D, survivin. [Joshua C. Curtin and Matthew V. Lorenzi. Drug Discovery Approaches to Target Wnt Signaling in Cancer Stem Cells. Oncotarget 1: 552, 2010].
Tankyrases play a key role in the destruction complex by regulating the stability of the rate-limiting AXIN proteins, RNF146 and tankyrase itself. The E3 ubiquitin ligase RNF146 recognizes tankyrase-mediated PARsylation and eartags AXIN, tankyrase and itself for proteasome-mediated degradation. Thus, tankyrases control the protein stability and turnover of key components of the destruction complex, and consequently the cellular levels of β-catenin [Shih-Min A. Huang, Yuji M. Mishina, Shanming Liu, Atwood Cheung, Frank Stegmeier, et al. Tankyrase inhibition stabilizes axin and antagonizes Wnt signalling. Nature 461:614, 2009, Yue Zhang, Shanming Liu, Craig Mickanin, Yan Feng, Olga Charlat, et al. RNF146 is a poly(ADP-ribose)-directed E3 ligase that regulates axin degradation and Wnt signalling. Nature Cell Biology 13:623-629, 2011].
Aberrant regulation of the Wnt/β-catenin signaling pathway is a common feature across a broad spectrum of human cancers and evolves as a central mechanism in cancer biology. First of all, Wnt overexpression could lead to malignant transformation of mouse mammary tissue [Klaus A, Birchmeier W. Wnt signalling and its impact on development and cancer. Nat Rev Cancer 8: 387-398, 2008]. Second, tumor genome sequencing discovered the mutations in Wnt/β-catenin pathway components as well as epigenetic mechanisms that altered the expression of genes relevant to Wnt/β-catenin pathway [Ying, Y. et al. Epigenetic disruption of the WNT/beta-catenin signaling pathway in human cancers. Epigenetics 4:307, 2009]. Third, Wnt/β-catenin pathway also cooperates with other oncogenic signaling pathways in cancer and regulates tumorigenesis, growth, and metastasis [Klaus A, Birchmeier W. Wnt signalling and its impact on development and cancer. Nat Rev Cancer 8: 387-398, 2008]. In addition, there is an additional role of WNT signaling between tumor and stromal cell interaction leading to tumorigenesis and metastasis [Shahi P, Park D, Pond A C, Seethammagari M, Chiou S-H, Cho K, et al. Activation of Wnt signaling by chemically induced dimerization of LRP5 disrupts cellular homeostasis. PLoS ONE 7: e30814, 2012]. Furthermore, growing body of evidence indicates a critical role of β-catenin in CSCs [Eaves C J, Humphries R K. Acute myeloid leukemia and the Wnt pathway. N Engl J Med. 362: 2326-7, 2010; Nusse R, Fuerer C, Ching W, Harnish K, Logan C, Zeng A, ten Berge D, Kalani Y. Wnt signaling and stem cell control. Cold Spring Harb Symp Quant Biol. 73: 59-66, 2008; Reya T, Clevers H. Wnt signalling in stem cells and cancer. Nature 434: 843-50, 2005]. For example, stem-like colon cells with a high level of β-catenin signaling have a much greater tumorigenic potential than counterpart cells with low β-catenin signaling [Vermeulen L, De Sousa E M F, van der Heijden M, Cameron K, de Jong J H, Borovski T, Tuynman J B, Todaro M, Merz C, Rodermond H, Sprick M R, Kemper K, Richel D J, Stassi G, Medema J P. Wnt activity defines colon cancer stem cells and is regulated by the microenvironment. Nat Cell Biol. 12: 468-76, 2010]. Finally, activation of Wnt/β-catenin signalling pathway is also one of the major mechanism causing tumor recurrence and drug resistance. All these provide clear rationale to develop therapeutics targeting Wnt/β-catenin signaling pathway for the treatment of cancer.
One of the approaches to inhibit Wnt/β-catenin signaling pathway is to target druggable tankyrases. Tankyrase 1 (TNKS1) and tankyrase 2 (TNKS2) are poly(ADP-ribosyl)ases that are distinguishable from other members of the enzyme family by the structural features of the catalytic domain, and the presence of a sterile a-motif multimerization domain and an ankyrin repeat protein-interaction domain. Inhibition of TNKS blocks PARsylation of AXIN1 and AXIN2 and prevents their proteasomal degradation. As the consequence, TNKS inhibition enhances the activity of the β-catenin destruction complex and suppresses β-catenin nuclear transclocation and the expression of β-catenin target genes.
In addition to its function in Wnt signaling through modulation of β-catenin destruction, tankyrases are also implicated in other cellular functions, including telomere homeostasis, mitotic spindle formation, vesicle transport linked to glucose metabolism, and viral replication. In these processes, tankyrases interact with target proteins, catalyze poly (ADP-ribosyl)ation, and regulate protein interactions and stability. For example, TNKS1 controls telomere homeostasis, which promotes telomeric extension by PARsylating TRF1. TRF1 is then targeted for proteasomal degradation by the E3 ubiquitin ligases F-box only protein 4 and/or RING finger LIM domain-binding protein (RLIM/RNF12), which facilitates telomere maintenance [Donigian J R and de Lange T. The role of the poly(ADP-ribose) polymerase tankyrase1 in telomere length control by the TRF1 component of the shelterin complex. J Biol Chem 282:22662, 2007]. In addition, telomeric end-capping also requires canonical DNA repair proteins such as DNA-dependent protein kinase (DNAPK) TNKS1 stabilizes the catalytic subunit of DNAPK (DNAPKcs) by PARsylation [Dregalla R C, Zhou J, Idate R R, Battaglia C L, Liber H L, Bailey S M. Regulatory roles of tankyrase 1 at telomeres and in DNA repair: suppression of T-SCE and stabilization of DNA-PKcs. Aging 2(10):691, 2010]. Altered expression of TNKS1 and/or TNKS2, as well as genetic alterations in the tankyrase locus, have been detected in multiple tumors, e.g. fibrosarcoma, ovarian cancer, glioblastoma, pancreatic adenocarcinoma, breast cancer, astrocytoma, lung cancer, gastric cancer, and colon cancer [Lari Lehti, Nai-Wen Chi and Stefan Krauss. Tankyrases as drug targets. FEBS Journal 280: 3576, 2013]. In addition, tankyrases appear to have impact on viral infections. For example, HSV infection, it was shown that the virus cannot replicate efficiently in cells that with depletion of both TNKS1 and TNKS2.
Furthermore, a connection between tankyrases and glucose metabolism has been indicated. Thus, DNA polymorphism in a chromosomal region encoding tankyrase/methionine sulfoxide reductase A is robustly associated with early-onset obesity. TNKS1 knockout mice appeared to have reduced fat pads, suggesting a potential connection of TNKS and obesity. TNKS may also play a role in tissue fibrosis.
In summary, tankyrases are promising drug targets in regulating WNT signalling, telomere length (e.g. telomere shortening and DNA damage induced cell death), lung fibrogenesis, myelination and viral infection. The invention presented here describes a novel class of tankyrase inhibitors and their potential clinical utility for the treatment of various diseases, such as cancer, aging, metabolic diseases (e.g. diabetes and obesity), fibrosis (e.g. lung fibrogenesis) and viral infection.
The following list of selected references relates to inhibitors of TNKS1 and/or TNKS2 described in the literature or in patents. However, the chemical structures and compound classes of the inhibitors described in these references are completely different from the chemical structures of the present invention:
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WO 2008/042283 (Exelixis) discloses imidazole-4,5-dicarboxamide derivatives as JAK2 modulators.
WO 2001/000575 discloses heterocyclic dicarboxylic acid diamide derivatives as insecticides, including amido-substituted azole compounds.
However, the state of the art described above does not describe the specific substituted amido-substituted azole compounds of general formula (I) of the present invention as defined herein, i.e. an imidazole or an oxazole moiety, bearing:                in its 4-position, a group of structure:        
                                    wherein:                            * indicates the point of attachment of said groups with the rest of the molecule, and                R1 represents —OR9, or —N(R10)R11, which are as defined herein,and                                                in its 5-position, a group of structure:        
                                    wherein:                            * indicates the point of attachment of said groups with the rest of the molecule, and                X2 represents CR6 or N, and R4, R5, R6, R7 and R8 are as defined herein,and                                                in its 2-position, a substituent R2,                    wherein:                            R2 represents a group selected from hydrogen, C1-C3-alkyl, or C3-C4-cycloalkyl;or a stereoisomer, a tautomer, an N-oxide, a hydrate, a solvate, or a salt thereof, or a mixture of same, as described and defined herein, and as hereinafter referred to as “compounds of the present invention”, or their pharmacological activity.                                                
It has now been found, and this constitutes the basis of the present invention, that said compounds of the present invention have surprising and advantageous properties.
In particular, said compounds of the present invention have surprisingly been found to effectively inhibit TNKS1 and/or TNKS2 and may therefore be used for the treatment or prophylaxis of diseases of uncontrolled cell growth, proliferation and/or survival, inappropriate cellular immune responses, or inappropriate cellular inflammatory responses or diseases which are accompanied with uncontrolled cell growth, proliferation and/or survival, inappropriate cellular immune responses, or inappropriate cellular inflammatory responses mediated by TNKS1 and/or TNKS2 and/or mediated by the Wnt pathway, for example, haematological tumours, solid tumours, and/or metastases thereof, e.g. leukaemias and myelodysplastic syndrome, malignant lymphomas, head and neck tumours including brain tumours and brain metastases, tumours of the thorax including non-small cell and small cell lung tumours, gastrointestinal tumours, endocrine tumours, mammary and other gynaecological tumours, urological tumours including renal, bladder and prostate tumours, skin tumours, and sarcomas, and/or metastases thereof. Compounds of the present invention may additionally show improved selectivity for TNKS1 and/or TNKS2 (e.g. over other PARP (poly(ADP-ribose)-polymerase) enzymes), for the treatment of TNKS1 and/or TNKS2 driven diseases, by reaching sufficient efficacious dose without inducing toxicity driven by, for example, other PARPs inhibition.